price of art auctioneer sothebys, which, he has found, also tends to peak just before a bubble pops. >> in 1989, when sothebys stock hit a new high, it was world record art prices paid by japanese buyers that set that stock on fire. >> reporter: two months later, japans nikkei index hit its peak: nearly 40,000. today, it slouches at around 10,000. as for sothebys... >> in 1999, the stock again hit a new high, this time the buying pressure was coming from those who had generated wealth through the technology, media and telecom sector. >> reporter: wealth that popped when the tech bubble burst in 2000. >> stock hit a new high in may of 2007, this time world record art prices being set by buyers from emerging markets, hedge fund billionaires, private equity billionaires, beneficiaries of easy money.